Oculus Twinfield 2
Another in the series of high quality devices of the German company Oculus owned by “Perfect Vision”. The experience gained in fifty years of visual field testing has placed this company’s devices among the most highly regarded in Europe and worldwide. Their reliability is best illustrated by the fact that it is precisely Twinfield 2 that has been recommended by the German Ophthalmological Society for all perimetric examinations. Computerized perimetry is a computerized examination of the functionality of the visual field, after which any defects in it can be detected on a graphic display.rnrn rnrnComputerized visual field is most commonly used in glaucoma testing, because the device can reveal early changes of this disease that the patient usually cannot notice on their own. Twinfield 2 is also used for neurological examinations as well as for checking macular function when age related degeneration is suspected.
Static and kinetic testing
The Twinfield 2 perimeter tests the full visual field using automatic static as well as automatic or manual kinetic examinations. Automatic static examination stands out for its exceptional precision and speed when it comes to testing both the central part of the visual field and the periphery, which is achieved by a dense arrangement of test points, especially in the macular area. This dense arrangement of stimulating points is what sets Twinfield 2 apart from competing devices, because it also takes into account the physiology of the retina itself.rnrnThe test points are illuminated alternately and the patient confirms that they have seen them by pressing a button. In this way, the Twinfield 2 software records the points that have been seen, and every failure to notice a stimulating point is categorized as a defect that may be located in different areas. The localization of the points seen and of the defects is compared with possible defects that are in line with the patient’s age, after which the system provides a final, easy to understand, standardized finding.
Reliable diagnostic value
Automatic kinetic examination is based on Goldman principles of visual field assessment. The Goldman kinetic principle implies that the stimulating points move from the periphery toward the center, and the patient’s task is to press the button as soon as they notice the point. The procedure is repeated by moving the stimulus toward the center of the visual field from different directions. In this way the boundaries of the visual field can be easily detected.rnrnThe Twinfield 2 perimeter has exceptional diagnostic value and reliability. This is achieved by the top level components and software integrated into the device. A high resolution (CMOS) camera monitors the position of the eye throughout the entire test, registers every significant loss of fixation and promptly notifies the medical staff. The technician can promptly warn the patient to refocus their gaze or change the position of their head, thereby reducing the possibility of unreliable findings. The system also records every unnecessary button press (when no point has been illuminated and the patient presses the button), which reduces the percentage of false positive errors.
The special “Glaucoma staging program” additionally helps the ophthalmologist in the analysis of the findings. The SPARK strategy is based on a database of 90,000 different cases and enables fast testing with a wealth of information important for the detection, prognosis and control of glaucoma. Various grids of stimulating points are available to the ophthalmologist, from those that cover only the macula to those that include the entire visual field. These include the 30-2, 30-2 bs, 24-2, 24-2 bs, 10-2, Esterman, physiological (zones 1–8), FeV-70 and other grids. The size of the field being tested is 90°, which means the entire visual field.
